As Spinal Tap and Steel Panther can attest, translating a musical gag into a standard concert setting is a recipe designed to kill the joke on the spot. But even in an acoustic setting that meant no stage set and no band (hence the band introductions, “On drums, no one; on keyboards no one”) Tenacious D made it work both musically and comedically.

Two too-tubby types in too-big T-shirts, Jack Black (star of Kung-Fu Panda and Shallow Hal) and sidekick Kyle “Kage” Gass’s humour was sweary, heroically silly and, at times, laugh-out loud funny: “This is a song for all the roadies out there. It’s called Roadie.” Crucially, though, like Flight of the Conchords, they could back the laughs with the songs, most of which cast the pair as a cheeky Everly Brothers, even when they were occasionally joined by two handclapping backing vocalists, one of whom was dressed in a Sasquatch costume.

Gass was a surreptitiously adept guitarist, Black’s voice was helpfully clear, but Throw Down, Rock Is Dead (cleverly entwined with Led Zeppelin’s Rock and Roll) and Friendship (“as long as there’s a record deal we’ll always be friends”) would have stood up without the daftness.

The crowd helped too, so in on the joke that they joined in word for word on the mostly spoken Tribute and cheerily booed when Gass briefly quit the duo as he does every night before Dude (I Totally Miss You). But the standing ovation at the end was as genuine as they come. Tenacious D may mock rock but they adore it too.